The clinical significance of autoantibodies to a soluble cytoplasmic antigen in systemic lupus erythematosus and other connective tissue diseases.

Seventy-two patients were studied whose sera contained antibodies to a cytoplasmic antigen, RO. The majority had clinical features typical of systemic lupus erythematosus and there appeared to be an overlap with Sjögren's syndrome. Of interest is that certain patients with lupus respond predominantly to cytoplasmic antigens and in some cases were ANA negative. Demonstration of this system is important in enlarging the serologic spectrum characteristic of SLE patients, and also may be an important marker for systemic disease in patients with predominantly cutaneous involvement.